A recipe multiplier describes how much batter would preserve average depth. Heat transfer depends on more variables than that single geometric ratio contains.
Thickness changes the path heat must travel
Using the same unscaled batter in a wider pan makes a thinner layer, while scaling by area aims to restore the original average depth. Even then, edge distance and centre distance change with shape. A rectangle, square, and circle of equal area do not expose every point to the same heating path.
Material, colour, and oven behavior matter
Metal gauge, dark coatings, glass, ceramic, convection, rack position, preheating, and actual thermostat accuracy can all alter heating. PanRatio has no sensor or tested recipe data, so it deliberately leaves the recipe temperature unchanged and provides no automatic time adjustment.
Follow the recipe and check doneness directly
Treat the calculated factor as a quantity-planning aid. Use the recipe author’s pan notes, safe fill level, visual and tactile cues, an appropriate thermometer when relevant, and food-safety guidance. Start checking thoughtfully rather than converting minutes by the area percentage.